The invention relates to display systems, and more particularly, to display systems with multifunctional digitizer module board.
Many types of touch sensing devices, like digitizers etc. currently are used on or in conjunction with computer displays. Such touch sensing devices measure the position of position pointer or finger contact on the sensor surface and generates coordinates for interaction with the computer, for example in selecting icons on the display, menu items, editing images, and feedback for input of hand-drawn characters and graphics.
Such touch sensing devices may use any number of technologies, including capacitive sensing, resistive sensing using a conductive overlay sheet, infrared sensing, acoustic wave sensing, and piezoelectric force sensing. Digitizers which use hardwired handheld position pointer such as pens typically use electromagnetic, electrostatic, resistive, or sonic pulse sensing.
Touch sensing devices responsive to human contact are typically used for cursor control, such as selection of display icons and menu items or responsive to position pointer (usually a hardwired pen) are used to create or trace drawings, blueprints, or original art. These touch sensing devices are also used for character or handwriting recognition. It is therefore desirable that the touch sensing devices reproduce the path of the position pointer by some visual means to provide visual feedback.
Some of these touch sensing devices are responsive to both user and position pointer contact, thereby providing the convenience of position pointer-based input, for example when writing on the screen, as well as the ease of touch input, which does not require position pointer.
FIG. 1 is a structural diagram of a conventional display device with a digitizer. As shown, the display device 200 comprises a top glass cover 210, the liquid crystal display (LCD) panel 220, a back light module 230, a reflector 240, the digitizer sensor board 250, a shield film 260, a back frame 270 and a position pointer 280. The top glass cover 210, the LCD panel 220, the back light module 230, the reflector 240, the digitizer sensor board 250, the shield film 260 and the back frame 270 are assembled as a laminated construction, and the digitizer sensor board 250 and the position pointer 280 constructing a digitizer. The LCD panel 220 and the digitizer sensor board 250 are coupled to an external host system via differential interfaces, such as two flexible printed circuit boards (FPCs). FIG. 2 is a circuit diagram of a conventional display system 100 which comprises LCD module 110 and digitizer module board 120. The LCD module 220 and the digitizer module board 120 are coupled to the host system 130 via corresponding interfaces 112 and 122 respectively. The digitizer module board 120 requires an oscillator 124 disposed in the microcontroller 126 to generate scan timing signals (not shown) for the selection circuit 128, thereby performing scan operation of digitizer sensor array 129. Because the reflector, the digitizer sensor board, a shield film and a back frame in the conventional display system are separate components and the LCD panel and the digitizer sensor board require differential interfaces coupled to an external host system, the conventional display system presents higher cost, thickness, and weight.